In recent years, a motor rotating at a high speed and having a relatively large capacity is increasingly used as a driving motor of an electric vehicle, a hybrid vehicle, and the like. For this reason, an iron core material to be used for a driving motor is required to have achievement of low core loss in a range of several hundred Hz to several kHz higher than a commercial frequency. Further, an iron core to be used for a rotor is also required to have a certain mechanical strength in order to withstand a centrifugal force and a stress variation. An iron core material to be used for other than a driving motor of a vehicle sometimes needs to have such a requirement.
Conventionally, some techniques have been proposed whose purposes are core loss reduction, strength improvement and/or the like (Patent Literatures 1 to 12).
However, with these techniques, it is difficult to attain achievement of the core loss reduction and the strength improvement. Further, some of the techniques have difficulty in actually manufacturing a non-oriented electrical steel sheet.